The bottom panels in Fig. REF  show the change of ratios from matching \(N_{\mathrm {ch}}\)  to matching \(c\)  via Eq. (). The insert panel in Fig. REF (c) shows the same \(\Delta R_{\left\langle p_{\mathrm {T}}\right\rangle }\)  but plotted as a function centrality. Since \(\left\langle p_{\mathrm {T}}\right\rangle \)  increases with \(N_{\mathrm {ch}}\)  (or decreases with centrality), the difference \(\Delta R_{\left\langle p_{\mathrm {T}}\right\rangle }\)  is positive according to Eq.  Note that if we calculate instead the change of ratio from the same \(c\)  to the same \(N_{\mathrm {ch}}\) , as is done in all other figures via Eq. (REF ), the results would have the opposite signs.. \(\Delta R_{\left\langle p_{\mathrm {T}}\right\rangle }\)  reaches a value of \(\sim 0.0005\)  at \(c= 0.2\) , \(\sim 0.002\)  at \(c=0.5\) , and even larger in more peripheral collisions. This difference is potentially a significant fraction of the signal, \(R_{\left\langle p_{\mathrm {T}}\right\rangle }-1\) , as a function of centrality, which is predicted to be \(\sim 0.003\)  at \(c= 0.2\)  and \(\sim 0.005\)  at \(c=0.5\)  in a hydrodynamic model simulation with nuclear structure parameters close to those in Tab. REF  [1]}. The impact of switching the event activity variable is generally smaller in more central collisions. On the other hand, since \(\sigma _{p_{\mathrm {T}}}/\left\langle p_{\mathrm {T}}\right\rangle \)  increases with centrality (or decreases with \(N_{\mathrm {ch}}\) ), the difference in its ratio is negative, with a magnitude of \(\sim 0.01\)  at \(c= 0.2\) , which increases to \(\sim 0.03\)  at \(c= 0.5\) . The comparison with the AMPT simulations shows that the difference in the diffuseness parameter between the isobaric systems plays the dominant role.
